Transmission device, transmission method, reception device, and reception method for a first stream having encoded image data of pictures on a low-level side and a second stream having encoded image data of pictures on a high-level side

ABSTRACT

An image data of pictures constituting moving image data is encoded to generate an encoded video stream. In this case, the image data of the pictures constituting the moving image data is classified into a plurality of levels and encoded to generate a video stream having the image data of the pictures at the respective levels. Hierarchical composition is equalized between a low-level side and a high-level side, and corresponding pictures on the low-level side and the high-level side are combined into one set and are sequentially encoded. This allows a reception side to decode the encoded image data of the pictures on the low-level side and the high-level side with a smaller buffer size and a reduced decoding delay.

TECHNICAL FIELD

The present invention relates to a transmission device, a transmission method, a reception device, and a reception method, more specifically, to a transmission device that subjects image data of pictures constituting moving image data to hierarchical encoding and transmits the same, and others.

BACKGROUND ART

To service compressed moving images by way of broadcasting, networks, or the like, there is an upper limit on replayable frame frequency depending on decoding capability of a receiver. Therefore, service providers need to limit their services to low-frame frequency services or provide concurrently high-frame frequency services and low-frame frequency services, with consideration given to replaying capabilities of the prevailing receivers.

To correspond to high-frame frequency services, the receivers become higher in cost, which is a disincentive to popularization. When inexpensive receivers dedicated to low-frame frequency services are initially in widespread use and service providers start high-frame frequency services in the future, customers cannot receive the high-frame frequency services without new receivers, which is a disincentive to proliferation of the new services.

For example, there is proposed time-direction scalability by subjecting image data of pictures constituting moving image data to hierarchical encoding by high efficiency video coding (HEVC) (refer to Non-patent Document 1). At the reception side, the levels of the pictures can be identified based on temporal ID (temporal_id) information inserted in the header of a network abstraction layer (NAL) unit, which allows selective decoding up to the level corresponding to decoding capability.

CITATION LIST Non-Patent Document

-   Non-patent Document 1: Gary J. Sullivan, Jens-Rainer Ohm, Woo-Jin     Han, Thomas Wiegand, “Overview of the High Efficiency Video Coding     (HEVC) Standard” IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO     TECNOROGY, VOL. 22, NO. 12, pp. 1649-1668, DECEMBER 2012

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

An object of the subject technique is to allow favorable decoding at the reception side.

Solutions to Problems

A concept of the subject technique lies in a transmission device including:

an image encoding unit that classifies image data of pictures constituting moving image data into a plurality of levels and encodes the classified image data of the pictures at the respective levels to generate a video stream having the encoded image data of the pictures at the respective levels; and

a transmission unit that transmits a container in a predetermined format containing the generated video stream, wherein

the image encoding unit equalizes hierarchical composition between a low-level side and a high-level side, and combines corresponding pictures on the low-level side and the high-level side into one set and encodes the same sequentially.

According to the subject technique, the image encoding unit encodes the image data of the pictures constituting the moving image data to generate the video stream (encoded stream). In this case, the image data of the pictures constituting the moving image data is classified into a plurality of levels and encoded to generate the video stream having the image data of the pictures at the respective levels. The hierarchical composition is equalized between the low-level side and the high-level side. Corresponding pictures on the low-level side and the high-level side are combined into one set and are sequentially encoded.

The transmission unit transmits the container in the predetermined format including the foregoing video stream. For example, the image encoding unit may generate a single video stream having the encoded image data of the pictures at the respective levels or divide the plurality of levels into two sets of the upper-level side and the lower-level side and generate two video streams having the encoded image data of the pictures in the respective level sets.

According to the subject technique, the hierarchical composition is equalized between the low-level side and the high-level side, and corresponding pictures on the low-level side and the high-level side are combined into one set and are sequentially encoded. This allows the reception side to decode the encoded image data of the pictures on the low-level side and the high-level side with a smaller buffer size and a reduced decoding delay.

In the subject technique, for example, a hierarchical information insertion unit that inserts hierarchical information into a layer of the container may further be included. In this case, for example, the hierarchical information may have information on level specified values for the respective levels. In addition, in this case, for example, the hierarchical information insertion unit may insert the hierarchical information into the layer of the container at positions in synchronization with the encoded image data of the pictures in the video stream.

For example, the hierarchical information insertion unit may insert the hierarchical information into an extension field of a PES packet. In this case, the hierarchical information insertion unit may insert the hierarchical information into the extension field of the PES packet at least for each coded video sequence. In addition, in this case, for example, an information insertion unit that inserts information for describing explicitly whether the hierarchical information is inserted into the extension field of the PES packet may further be included under a program map table.

In addition, for example, the hierarchical information insertion unit may insert the hierarchical information under a program map table. In addition, for example, the hierarchical information insertion unit may insert the hierarchical information under an event information table.

The hierarchy information is inserted in the layer of the container, and the reception side can refer to the hierarchy information to retrieve selectively from the video stream the encoded image data of the pictures up to the level commensurate with the capability of the decoder in an easy manner.

In addition, another concept of the subject technique lies in a reception device including a reception unit that receives a container in a predetermined format that contains a video stream having encoded image data of pictures obtained by classifying image data of the pictures constituting moving image data into a plurality of levels and encoding the same, wherein

in the encoding, hierarchical composition is equalized between a low-level side and a high-level side, and corresponding pictures on the low-level side and the high-level side are combined into one set and are sequentially encoded, and

the reception device further includes a processing unit that processes the received container.

According to the subject technique, the reception unit receives the container in the predetermined format. The container contains the video stream having image data of the pictures at the respective levels obtained by classifying the image data of the pictures constituting the moving image data into a plurality of levels and encoding the same. In this case, in the process of encoding, the hierarchical composition is equalized between the low-level side and the high-level side, and corresponding pictures on the low-level side and the high-level side are combined into one set and are sequentially encoded.

The processing unit processes the received container. For example, the processing unit may be configured to retrieve selectively the encoded image data of the pictures at a predetermined level and lower ones from the video stream and decode the same based on the hierarchy information, thereby obtaining the image data of the pictures at the predetermined level and lower ones.

As described above, according to the subject technique, in the video stream contained in the received container, the hierarchical composition is equalized between the low-level side and the high-level side, and corresponding pictures on the low-level side and the high-level side are combined into one set and are sequentially encoded. This makes it possible to decode the encoded image data of the pictures on the low-level side and the high-level side with a smaller buffer size and a reduced decoding delay.

According to the subject technique, hierarchical information may be inserted into a layer of the container, and

the processing unit may retrieve selectively from the video stream the encoded image data of the pictures at a predetermined level and lower ones and decode the same, based on the hierarchical information, to obtain the image data of the pictures at the predetermined level and lower ones. In this case, it is easy to retrieve selectively from the video stream the encoded image data of the pictures at the level commensurate with the capability of the decoder in an easy manner.

Effects of the Invention

According to the subject technique, the reception side can perform favorable decoding. The advantages of the technique are not limited to the ones described here but may be any of advantages described in the subject disclosure.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of a transmission/reception system as an embodiment.

FIG. 2 is a block diagram of a configuration example of a transmission device.

FIG. 3 is a diagram illustrating an example of hierarchical encoding performed by an encoder.

FIGS. 4(a) and 4(b) are diagrams illustrating a structural example (Syntax) of an NAL unit header and the contents (Semantics) of major parameters in the structural example.

FIG. 5 is a diagram illustrating another example of hierarchical encoding performed by the encoder.

FIG. 6 is a diagram illustrating a configuration example of encoded image data of pictures.

FIGS. 7(a) and 7(b) are diagrams illustrating a structural example (Syntax) of a layer decoding descriptor (Layer_decoding_descriptor).

FIG. 8 is a diagram illustrating the contents (Semantics) of major information in the structural example of the layer decoding descriptor.

FIG. 9 is a diagram illustrating a structural example (Syntax) of a PES extension field data “pes_extension_field_data( )”.

FIGS. 10(a) and 10(b) are diagrams illustrating a structural example (Syntax) of a PES extension descriptor (PES_extension_descriptor) and the contents (Semantics) of major information in the structural example.

FIG. 11 is a diagram of a configuration example of a transport stream TS in the case where single-stream distribution is performed and hierarchical information is inserted under a program map table.

FIG. 12 is a diagram of a configuration example of the transport stream TS in the case where two-stream distribution is performed and hierarchical information is inserted under the program map table.

FIG. 13 is a diagram of a configuration example of the transport stream TS in the case where single-stream distribution is performed and hierarchical information is inserted under an event information table.

FIG. 14 is a diagram of a configuration example of the transport stream TS in the case where two-stream distribution is performed and hierarchical information is inserted under the event information table.

FIG. 15 is a diagram of a configuration example of the transport stream TS in the case where single-stream distribution is performed and hierarchical information is inserted into an extension field of a PES packet header.

FIG. 16 is a diagram of a configuration example of the transport stream TS in the case where two-stream distribution is performed and hierarchical information is inserted into the extension field of the PES packet header.

FIG. 17 is a block diagram illustrating a configuration example of a reception device.

FIG. 18 is a diagram illustrating an example of correspondence between signaling of “level_idc” and hierarchical information of coded image data with changes in hierarchical composition.

MODE FOR CARRYING OUT THE INVENTION

An embodiment for carrying out the invention (hereinafter, referred to as “embodiment”) will be described below. The descriptions will be given in the following order:

1. Embodiment

2. Modification example

<1. Embodiment>

[Transmission/Reception System]

FIG. 1 illustrates a configuration example of a transmission/reception system 10 as an embodiment. The transmission/reception system 10 has a transmission device 100 and a reception device 200.

The transmission device 100 transmits a transport stream TS as a container carried on broadcast waves or in packets over a network. The transport stream TS contains a video stream in which image data of pictures constituting moving image data is classified into a plurality of levels and encoded data of the image data of the pictures at the respective levels is included. In this case, the transport stream TS contains a single video stream having the encoded image data of the pictures at the respective levels or two video streams in which the plurality of levels is divided into two sets of high-level side and low-level side and the encoded image data of the pictures at the respective level sets is included.

For example, the referenced pictures are encoded according to H.264/AVC or H.265/HEVC such that they belong to their levels and/or lower ones. In this case, the hierarchical composition is equalized between the low-level side and the high-level side, and corresponding pictures on the low-level side and the high-level side are combined into one set and are sequentially encoded. Performing such encoding allows the reception side to decode the encoded image data of the pictures on the low-level side and the high-level side with a smaller buffer size and a reduced decoding delay.

Level identification information is added to the encoded image data of the pictures at the respective levels to identify the levels to which the pictures belong. In the embodiment, the level identification information (“nuh_temporal_id_plus1” indicative of temporal_id) is added to the headers of the NAL units (nal_unit) of the pictures. Adding the level identification information allows the reception side to retrieve selectively the encoded image data at the predetermined level and lower ones for decode processing.

Hierarchical information including information on level specified values at the respective levels and others is inserted into the layer of the container. The reception side can refer to the hierarchical information to retrieve selectively from the video stream the encoded image data of the pictures at the level commensurate with the capability of the decoder in an easy manner. For example, the hierarchical information is inserted under a program map table (PMT) or under an event information table (EIT).

In addition, the hierarchical information is inserted into PES extension fields of the headers of PES packets at positions in synchronization with the encoded image data of the pictures in the video stream, for example. This allows the reception side to, even with changes in the hierarchical composition, retrieve selectively from the video stream the encoded image data of the pictures at the level commensurate with the capability of the decoder.

When the hierarchical information is inserted into the extension field of the PES packet as described above, identification information indicating that the hierarchical information is inserted into the extension field of the PES packet is inserted under the program map table. In this case, the reception side can identify a situation that the hierarchical information is inserted into the extension field of the PES packet based on the identification information.

The reception device 200 receives the transport stream TS sent from the transmission device 100 on broadcast waves or in packets over a network. The reception device 200 processes the transport stream TS. In this case, the reception device 200 retrieves selectively from the video stream the encoded image data of the pictures at a predetermined level and lower ones commensurate with the capability of the decoder and decodes the same based on the hierarchy information contained in the layer of the container, thereby obtaining the image data of the pictures at the predetermined level and lower ones.

“Configuration of the Transmission Device”

FIG. 2 illustrates a configuration example of the transmission device 100. The transmission device 100 has a central processing unit (CPU) 101, an encoder 102, a compressed data buffer (cpb: coded picture buffer) 103, a multiplexer 104, and a transmission unit 105. The CPU 101 is a control unit that controls the operations of the components of the transmission device 100.

The encoder 102 inputs uncompressed moving image data VD to perform hierarchical encoding. The encoder 102 classifies the image data of pictures constituting the moving image data VD into a plurality of levels. Then, the encoder 102 encodes the classified image data of the pictures at the respective levels to generate a video stream having the encoded image data of the pictures at the respective levels.

The encoder 102 performs encoding such as H.264/AVC or H.265/HEVC. At that time, the encoder 102 performs encoding such that the referenced pictures belong to their levels and/or lower ones. The encoder 102 also divides the plurality of levels into low-level side and high-level side, and equalizes the hierarchical composition between the low-level side and the high-level side, and combines corresponding pictures on the low-level side and the high-level side into one set and encodes the same sequentially.

FIG. 3 illustrates an example of hierarchical encoding performed by the encoder 102. In this example, the image data of the pictures is classified into six levels of 0 to 5, and is subjected to encoding.

The vertical axis indicates the levels. The values 0 to 5 are set as the temporal_id (level identification information) added to the headers of the NAL units (nal_unit) constituting the encoded image data of the pictures at the levels 0 to 5. Meanwhile, the horizontal axis indicates the picture order of composition (POC), the display time is earlier with increasing proximity to the left side and is later with increasing proximity to the right side.

FIG. 4(a) illustrates a structural example (Syntax) of the NAL unit header, and FIG. 4(b) illustrates the contents (Semantics) of major parameters in the structural example. The 1-bit field “Forbidden_zero_bit” is essentially 0. The 6-bit field “Nal_unit_type” indicates the NAL unit type. The 6-bit field “Nuh_layer_id” is 0 as a precondition. The 3-bit field “Nuh_temporal_id_plus1” indicates temporal_id and takes the value increased by one (1 to 6).

Returning to FIG. 3, rectangular frames indicate pictures, and numbers in the rectangular frames indicate the order of coded pictures, that is, the encoding order (the decoding order at the reception side). For example, eight pictures of “0” to “7” constitute a sub group of pictures, and the picture “0” becomes the first picture in the sub group of pictures. Several sub groups of pictures are collected into a group of pictures (GOP).

In this example, three levels of 0 to 2 are on the low-level side and three levels of 3 to 5 are on the high-level side. As illustrated in the drawing, the hierarchical composition is equalized between the low-level side and the high-level side, and corresponding pictures on the low-level side and the high-level side are combined into one set and are sequentially encoded. For example, the picture “0” on the low-level side and the picture “1” on the high-level side are first combined into one set and subjected to encoding, and then the picture “2” on the low-level side and the picture on the high-level side are combined into one set and subjected to encoding. The pictures at the following levels are encoded in the same manner. In this case, the low levels are limited to levels lower than a specific level. Accordingly, to decode the pictures at the low levels, only the pictures at the limited low levels can be decoded and displayed in a stable manner. This matter also applies even when the pictures are not divided into the low levels and the high levels.

Returning to FIG. 3, solid-line and broken-line arrows indicate the reference relationships between the pictures in encoding. For example, the picture “0” is an intra picture (I picture) that needs no reference to other pictures, and the picture “1” is a P picture that is encoded with reference to the “1” picture. The picture “2” is a B picture that is encoded with reference to the “0” picture and a picture in the previous sub group of pictures (not illustrated). The picture “3” is a B picture that is encoded with reference to the “0” and “2” pictures. Similarly, the other pictures are encoded with reference to pictures close to them in the picture order of composition. The code “D” indicates how much each picture is distant from the referenced picture in the picture order of composition. Without the indication of “D,” D=1.

FIG. 5 illustrates another example of hierarchical encoding performed by the encoder 102. Although no detailed description will be provided, in the example of FIG. 3, the picture order of composition on the high-level side is one picture behind the picture order of composition on the low-level side, whereas, in the example of FIG. 5, the picture order of composition on the high-level side is one picture ahead of the picture order of composition on the low-level side. In this case, the hierarchical composition is equalized between the low-level side and the high-level side, and corresponding pictures on the low-level side and the high-level side are combined into one set and are sequentially encoded.

The encoder 102 generates a video stream having the encoded image data of the pictures at the respective levels. For example, the encoder 102 generates a single video stream having the encoded image data of the pictures at the respective levels or generates two video streams having the encoded image data of the pictures on the upper-order level side and the lower-order level side.

FIG. 6 illustrates a configuration example of encoded image data of the pictures. The encoded image data of the first picture of the GOP is composed of NAL units of access unit delimiter (AUD), video parameter set (VPS), sequence parameter set (SPS), picture parameter set (PPS), picture supplemental enhancement information (PSEI), SLICE, slice supplemental enhancement information (SSEI), and end of sequence (EOS). Meanwhile, the pictures other than the first picture of the GOP are composed of NAL units of AUD, PPS, PSEI, SLICE, SSEI, and EOS. The unit VPS can be transmitted together with the unit SPS once per sequence (GOP), and the unit PPS can be transmitted for each picture. The unit EOS may not exist.

The bit stream level specified value “general_level_idc” is inserted into the sequence parameter set (SPS). In addition, when the pictures belonging to the levels indicated by “temporal_id” are bound into sub layers (sub_layer) and “Sublayer_level_presented_flag” is set to “1,” the bit rate level specified value for each sub layer “sublayer_level_idc” can also be inserted into the SPS. This matter is applied to not only the SPS but also the VPS.

For example, the example of hierarchical encoding illustrated in FIG. 3 will be discussed. The value of “general_level_idc” inserted into the SPS is a level value including all the pictures at the levels 0 to 5. For example, when the frame rate is 120P, the value is “Level 5.2.” The value of “sublayer_level_idc[2]” inserted into the SPS becomes a level value including only the pictures at the levels 0 to 2. For example, when the frame rate is 60P, the value is “Level 5.1.”

Returning to FIG. 2, the compressed data buffer (cpb) 103 accumulates temporarily the video stream containing the encoded image data of the pictures at the respective levels generated by the encoder 102. The multiplexer 104 reads the video stream accumulated in the compressed data buffer 103, turns the same into a PES packet, and further turns the same into a transport packet to multiplex the same, thereby obtaining a transport stream TS as a multiplexed stream. The transport stream TS contains one or more video streams as described above.

The multiplexer 104 inserts the hierarchical information into the layer of the container. The transmission unit 105 transmits the transport stream TS obtained by the multiplexer 104 on broadcast waves or in packets over a network to the reception device 200.

[Insertion of the Hierarchical Information]

The insertion of the hierarchical information by the multiplexer 104 will be further explained. The multiplexer 104 inserts the hierarchical information to the layer of the container by any of the following methods (A), (B), and (C), for example:

(A) Insert the hierarchical information under the program map table (PMT);

(B) Insert the hierarchical information under the event information table (EIT); and

(C) Insert the hierarchical information into the extension field of the header of the PES packet.

“Description of (A)”

The transport stream TS contains a PMT as program specific information (PSI). The PMT has a video elementary loop (video ES1 loop) with information related to each video stream. In the video elementary loop, information such as stream type and packet identifier (PID) is arranged and descriptors describing information related to each video stream are also arranged in correspondence with the video stream.

The multiplexer 104 inserts a layer decoding descriptor (Layer_decoding_descriptor) newly defined as one of the descriptors. FIGS. 7(a) and 7(b) illustrate a structural example (Syntax) of the layer decoding descriptor. FIG. 8 illustrates the contents (Semantics) of major information in the structural example.

The 8-bit field “Layer_decoding_descriptor_tag” indicates descriptor type, and in this example, layer decoding descriptor. The 8-bit field “Layer_decoding_descriptor_length” indicates the length (size) of the descriptor as the number of bytes of the subsequent “layer_information( ).”

FIG. 7(b) illustrates a structural example (Syntax) of “layer_information( ).” The 3-bit field “layer_minimum LMI” indicates the level (layer) indicated by the minimum value of “temporal_id.” The 3-bit field “layer_maximum LMX” indicates the level (layer) indicated by the maximum value of “temporal_id.” In this example, the number of layers to which “temporal_id” is assigned is (LMX−LMI+1). The 8-bit field “layer_level_idc[i]” indicates “level_idc” as level specified value of the bit rate at each level.

“Description of (B)”

The transport stream TS also contains EIT as SI (serviced information) for management of each event. The multiplexer 104 arranges the layer decoding descriptor described above (see FIGS. 7(a) and 7(b)) under the EIT. In this case, the multiplexer 104 also arranges a conventionally known component descriptor under the EIT to make a link with the PES stream.

“Description of (C)”

PES extension field can be provided in the header of the PES packet. The multiplexer 104 inserts PES extension field data having hierarchical information into the extension field. In this manner, the multiplexer 104 provides the PES extension field in the header of the PES packet to insert the PES extension field data having hierarchical information at least for each coded video sequence (CVS), for example. FIG. 9 illustrates a structural example (Syntax) of the PES extension field data “pes_extension_field_data( ).”

The “PES_extension field length” is given outside the syntax structure. The 8-bit field “start_sync_byte” indicates the code value representing the start of the extension field. The 8-bit field “extension_field_type” indicates the type of the extension field, which means the supply of hierarchical information in this example. The “layer_information( )” has fields “layer_minimum LMI,” “layer_minimum LMX,” and “layer_level_idc[i],” as described above (see FIG. 7(b)).

In this case, the multiplexer 104 arranges a PES extension descriptor (PES_extension_descriptor) as one of the descriptors in the video elementary loop to describe explicitly that the hierarchical information is inserted into the PES extension field.

FIG. 10(a) illustrates a structural example (Syntax) of the PES extension descriptor (PES_extension_descriptor). FIG. 10(b) illustrates the contents (Semantics) of major information in the structural example. The 8-bit field “PES_extention_descriptor_tag” indicates the type of the descriptor, which means the PES extension descriptor in this example.

The 8-bit field “PES_extention_descriptor_length” indicates the length (size) of the descriptor as the number of subsequent bytes. The 1-bit field “PES_extension_existed” indicates whether the PES extension field of the applicable PES stream is encoded. The value “1” indicates that the PES extension field is encoded, and the value “0” indicates that the PES extension field is not encoded.

[Configuration of the Transport Stream TS]

FIG. 11 illustrates a configuration example of the transport stream TS in the case where single-stream distribution is performed and the hierarchical information is inserted under the program map table (PMT) (the foregoing case (A)). In this configuration example, there is a PES packet “video PES1” of a video stream having image data encoded by HEVC of pictures at a plurality of levels, for example.

The encoded image data of the pictures have NAL units such as VPS, SPS, PPS, SLICE, and SEI. As described above, the level identification information (“nuh_temporal_id_plus1” indicative of temporal_id) for the picture is arranged in the headers of the NAL units. The level specified value of the bit stream “general_level_idc” is inserted into the SPS. In addition, the pictures belonging to the levels indicated by “temporal_id” are bound into sub layers (sub_layer) and “Sublayer_level_presented_flag” is set to “1,” whereby the bit rate level specified value for each sub layer “sublayer_level_idc” is inserted into the SPS.

The transport stream TS also contains the program map table (PMT) as program specific information (PSI). The PSI is information describing to which program each elementary stream contained in the transport stream belongs.

The PMT has a program loop describing information related to the entire program. The PMT also has an elementary loop with information related to each elementary stream. In this configuration example, there exists a video elementary loop (video ES loop).

In the video elementary loop, information such as stream type and packet identifier (PID) is arranged in correspondence with the video stream (video PES1), and descriptors describing information related to the video stream are also arranged. As one of the descriptors, the layer decoding descriptor (Layer_decoding_descriptor) described above is inserted.

For example, in the examples of hierarchical encoding illustrated in FIGS. 3 and 5, the contents described by the descriptor are as follows: “layer_minimum LMI”=0, “layer_maximum LMX”=5, “layer_level_idc[0]”=Level 5, “layer_level_idc[1]”=Level 5, “layer_level_idc[2]”=Level 5.1, “layer_level_idc[3]”=Level 5.2, “layer_level_idc[4]”=Level 5.2, and “layer_level_idc[5]”=Level 5.2.

FIG. 12 illustrates a configuration example of the transport stream TS in the case where two-stream distribution is performed and the hierarchical information is inserted under the program map table (PMT) (the foregoing case (A)). In this configuration example, a plurality of levels is divided into two sets of low-level side and high-level side, and there exist PES packets “video PES1” and “video PES2” of the video streams having image data encoded by HEVC of the pictures of the two sets, for example.

The encoded image data of the pictures on the low-level side have NAL units such as VPS, SPS, PPS, SLICE, and SEI. The hierarchical identification information (“nuh_temporal_id_plus1” indicative of temporal_id) of the picture is arranged in the header of the NAL units. The level specified value of the bit stream “general_level_idc” is inserted into the SPS. In addition, the pictures belonging to the levels indicated by “temporal_id” are bound into sub layers (sub_layer) and “sublayer_level_presented_flag” is set to “1,” whereby the bit rate level specified value for each sub layer “sublayer_level_idc” is inserted into the SPS.

Meanwhile, the encoded image data of the pictures on the high-level side have NAL units such as PPS and SLICE. The hierarchical identification information (“nuh_temporal_id_plus1” indicative of temporal_id) of the picture is arranged in the headers of the NAL units.

The transport stream TS also contains the program map table (PMT) as program specific information (PSI). The PSI is information describing to which program each elementary stream contained in the transport stream belongs.

The PMT has a program loop describing information related to the entire program. The PMT also has an elementary loop with information related to each elementary stream. In this configuration example, there exist two video elementary loops (video ES1 loop and video ES2 loop).

In the video elementary loop, information such as stream type and packet identifier (PID) is arranged in correspondence with the video streams (video PES1 and video PES2), and descriptors describing information related to the video streams are also arranged. As one of the descriptors, the layer decoding descriptor (Layer_decoding_descriptor) described above is inserted.

For example, in the examples of hierarchical encoding illustrated in FIGS. 3 and 5, the contents described by the descriptors corresponding to the PES packets “video PES1” and “video PES2” are as follows: the descriptor corresponding to the PES packet “video PES1” describes “layer_minimum LMI”=0, “layer_maximum LMX”=2, “layer_level_idc[0]”=Level 5, “layer_level_idc[1]”=Level 5, and “layer_level_idc[2]”=Level 5.1; and the descriptor corresponding to the PES packet “video PES1” describes “layer_minimum LMI”=3, “layer_maximum LMX”=5, “layer_level_idc[3]”=Level 5.2, “layer_level_idc[4]”=Level 5.2, and “layer_level_idc[5]”=Level 5.2.

FIG. 13 illustrates a configuration example of the transport stream TS in the case where single-stream distribution is performed and the hierarchical information is inserted under the event information table (EIT) (the foregoing case (B)). In this configuration example, as in the configuration example of FIG. 11, there exists the PES packet “video PES1” of the video stream having the image data encoded by HEVC of the pictures at a plurality of levels, for example.

The transport stream TS contains the program map table (PMT) as program specific information (PSI). The PSI is information describing to which program each elementary stream contained in the transport stream belongs.

The PMT has a program loop describing information related to the entire program. The PMT also has elementary loops with information related to each elementary stream. The PMT has a program loop describing information related to the entire program. The PMT also has an elementary loop with information related to each elementary stream. In this configuration example, there exists a video elementary loop (video ES loop). In the video elementary loop, information such as stream type and packet identifier (PID) is arranged in correspondence with the video stream (video PES1), and descriptors describing information related to the video stream are also arranged.

The transport stream TS also contains EIT as SI (serviced information) for management of each event. The layer decoding descriptor (Layer_decoding_descriptor) described above is arranged under the EIT. Although not explained in detail, the contents described by the descriptor are the same as those in the configuration example of FIG. 11. A conventionally known component descriptor is arranged under the EIT to make a link with the PES packet “video PES1.”

FIG. 14 illustrates a configuration example of the transport stream TS in the case where two-stream distribution is performed and the hierarchical information is inserted under the event information table (EIT) (the foregoing case (B)). In this configuration example, a plurality of levels is divided into two sets of low-level side and high-level side, and there exist PES packets “video PES1” and “video PES2” of the video streams having image data encoded by HEVC of the pictures of the two sets, for example, as in the configuration example of FIG. 12.

The transport stream TS also contains the program map table (PMT) as program specific information (PSI). The PSI is information describing to which program each elementary stream contained in the transport stream belongs.

The PMT has a program loop describing information related to the entire program. The PMT also has an elementary loop with information related to each elementary stream. In this configuration example, there exist two video elementary loops (video ES1 loop and video ES2 loop). In the video elementary loop, information such as stream type and packet identifier (PID) is arranged in correspondence with the video streams (video PES1 and video PES2), and descriptors describing information related to the video streams are also arranged.

The transport stream TS also contains EIT as serviced information (SI) for management of each event. The layer decoding descriptors (Layer_decoding_descriptor) corresponding to the PES packets “video PES1” and “video PES2” are arranged under the EIT. Although not explained in detail, the contents described by the descriptors are the same as those in the configuration example of FIG. 12. A conventionally known component descriptor is arranged under the EIT to make links with the PES packets “video PES1” and “video PES2.”

FIG. 15 illustrates a configuration example of the transport stream TS in the case where single-stream distribution is performed and the hierarchical information is inserted into the extension field of the header of the PES packet (the foregoing case (C)). In this configuration example, there is a PES packet “video PES1” of a video stream having image data encoded by HEVC of pictures at a plurality of levels, for example, as in the configuration example of FIG. 11.

A PES extension field is provided in the header of the PES packet, and PES extension field data “pes_extension_field_data( )” having “layer_information( )” is inserted into the PES extension field. Although not described in detail, the contents described in “layer_information( )” are the same as those described by the layer decoding descriptor in the configuration example of FIG. 11.

The transport stream TS also contains the program map table (PMT) as program specific information (PSI). The PSI is information describing to which program each elementary stream contained in the transport stream belongs.

The PMT has a program loop describing information related to the entire program. The PMT also has an elementary loop with information related to each elementary stream. In this configuration example, there exists a video elementary loop (video ES loop).

In the video elementary loop, information such as stream type and packet identifier (PID) is arranged in correspondence with the video streams (video PES1 and video PES2), and descriptors describing information related to the video streams are also arranged. As one of the descriptors, a PES extention descriptor (PES_extention_descriptor) is inserted. The PES extention descriptor is a descriptor to describe explicitly that the hierarchical information is inserted into the PES extension field.

FIG. 16 illustrates a configuration example of the transport stream TS in the case where two-stream distribution is performed and the hierarchical information is inserted into the extension field of the header of the PES packet (the foregoing case (C)). In this configuration example, a plurality of levels is divided into two sets of low-level side and high-level side, and there exist PES packets “video PES1” and “video PES2” of the video streams having image data encoded by HEVC of the pictures of the two sets, for example, as in the configuration example of FIG. 12.

A PES extension field is provided in the header of the PES packet “video PES1”, and PES extension field data “pes_extension_field_data( )” having “layer_information( )” is inserted into the PES extension field. Although not described in detail, the contents described in “layer_information( )” are the same as those described by the layer decoding descriptor corresponding to the PES packet “video PES1” in the configuration example of FIG. 12.

A PES extension field is provided in the header of the PES packet “video PES2”, and PES extension field data “pes_extension_field_data( )” having “layer_information( )” is inserted into the PES extension field. Although not described in detail, the contents described in “layer_information( )” are the same as those described by the layer decoding descriptor corresponding to the PES packet “video PES2” in the configuration example of FIG. 12.

The transport stream TS also contains the PMT (program map table) as PSI (program specific information). The PSI is information describing to which program each elementary stream contained in the transport stream belongs.

The PMT has a program loop describing information related to the entire program. The PMT also has an elementary loop with information related to each elementary stream. In this configuration example, there exist two video elementary loops (video ES1 loop and video ES2 loop).

In the video elementary loop, information such as stream type and packet identifier (PID) is arranged in correspondence with the video streams (video PES1 and video PES2), and descriptors describing information related to the video streams are also arranged. As one of the descriptors, a PES extention descriptor (PES_extention_descriptor) is inserted. The PES extention descriptor is a descriptor to describe explicitly that the hierarchical information is inserted into the PES extension field.

Operation of the transmission device 100 illustrated in FIG. 2 will be briefly described. Uncompressed moving image data VD is input into the encoder 102. The encoder 102 subjects the moving image data VD to hierarchical encoding. Specifically, the encoder 102 classifies image data of pictures constituting the moving image data VD into a plurality of levels and encodes the same, thereby generating a video stream having encoded image data of the pictures at the respective levels.

In this case, the referenced pictures are encoded such that they belong to their levels and/or lower ones. In this case, a plurality of levels is divided into two of low-level side and high-level side, and the hierarchical composition is equalized between the low-level side and the high-level side, and corresponding pictures on the low-level side and the high-level side are combined into one set and are sequentially encoded. Also in this case, a single video stream having the encoded image data of the pictures at the respective levels is generated, or two video streams having the encoded image data of the pictures on the upper-order level side and the lower-order level side are generated.

The video stream generated by the encoder 102 and containing the encoded data of pictures at the respective levels is supplied to the compressed data buffer (cpb) 103 and is temporarily accumulated there. The multiplexer 104 reads the video stream from the compressed data buffer 103, turns the same into PES packet, further turns the same into transport packet for multiplexing, thereby obtaining the transport stream TS as a multiplexed stream. The transport stream TS contains one or more video streams as described above.

When the multiplexer 104 generates the transport stream TS, the hierarchical information is inserted in the layer of the container under the program map table (PMT), under the event information table (EIT), or in the extension field of the header of the PES packet. The transport stream TS generated by the multiplexer 104 is sent to the transmission unit 105. The transmission unit 105 transmits the transport stream TS on broadcast waves or in packets over a network to the reception device 200.

“Configuration of the Reception Device”

FIG. 17 illustrates a configuration example of the reception device 200. The reception device 200 has a central processing unit (CPU) 201, a reception unit 202, a demultiplexer 203, and a compressed data buffer (cpb: coded picture buffer) 204. The reception device 200 also has a decoder 205, a decompressed data buffer (dpb: decoded picture buffer) 206, a post-processing unit 207, and a display unit 208. The CPU 201 constitutes a control unit that controls operations of the components of the reception device 200.

The reception unit 202 receives the transport stream TS on broadcast waves or in packets over a network transmitted from the transmission device 100. The demultiplexer 203 retrieves selectively from the transport stream TS the encoded image data of the pictures at the level commensurate with the capability of the decoder 205, and sends the same to the compressed data buffer (cpb: coded picture buffer) 204. In this case, the demultiplexer 203 refers to the value of “nuh_temporal_id_plus1” indicative of “temporal_id” arranged in the headers of the NAL units (nal_unit) of the pictures.

In this case, the demultiplexer 203 extracts the hierarchical information inserted in the layer of the container, recognizes “layer_level_idc” at the respective levels from the hierarchical information, and detects up to which level decoding is enabled according to the capability of the decoder 205. For example, in the examples of hierarchical encoding of FIGS. 3 and 5, it is assumed that “layer_level_idc[0]”=Level 5, “layer_level_idc[1]”=Level 5, “layer_level_idc[2]”=Level 5.1, “layer_level_idc[3]”=Level 5.2, “layer_level_idc[4]”=Level 5.2, and “layer_level_idc[5]”=Level 5.2. In this case, when the decoder 205 has a capability of 60P, that is, “Level 5.1,” the demultiplexer 203 detects that decoding is enabled up to the level 2. In addition, in this case, when the decoder 205 has a capability of 120P, that is, “Level 5.2,” the demultiplexer 203 detects that decoding is enabled up to the level 5.

The compressed data buffer (cpb) 204 accumulates temporarily the encoded image data of pictures at the respective levels sent from the demultiplexer 203. The decoder 205 reads and decodes the encoded image data of the pictures accumulated in the compressed data buffer 204 at decode timings given by decoding time stamps (DTS) of the pictures, and sends the same to the decompressed data buffer (dpb) 206.

The decompressed data buffer (dpb) 206 accumulates temporarily the image data of the pictures decoded by the decoder 205. The post-processing unit 207 matches the frame rate for the image data of the pictures read sequentially at display timings given by presentation time stamps (PTS) from the decompressed data buffer (dpb) 206 with the display capability.

For example, when the frame rate of image data of the pictures after decoding is 60 fps and the display capability is 120 fps, the post-processing unit 207 performs interpolation in the image data of the pictures after decoding such that the time-direction resolution becomes doubled, and sends the same as image data of 120 fps to the display unit 208.

The display unit 208 is composed of a liquid crystal display (LCD), an organic electro-luminescence (EL) panel, or the like, for example. The display unit 208 may be an external device connected to the reception device 200.

Operations of the reception device 200 illustrated in FIG. 17 will be described briefly. The reception unit 202 receives the transport stream TS on broadcast waves or in packets over a network from the transmission device 100. The transport stream TS is sent to the demultiplexer 203. The demultiplexer 203 retrieves selectively from the transport stream TS the encoded image data of pictures at the level commensurate with the capability of the decoder 205 based on the hierarchical information inserted in the layer of the container, and sends the same to the compressed data buffer (cpb) 204 for temporary accumulation.

The decoder 205 retrieves the encoded image data of pictures at the respective levels accumulated in the compressed data buffer 204. The decoder 205 then decodes the retrieved encoded image data of the pictures at the respective decode timings for the pictures, sends the same to the decompressed data buffer (dpb) 206 for temporary accumulation.

Then, the image data of the pictures read sequentially at the display timings from the decompressed data buffer (dpb) 206 is sent to the post-processing unit 207. The post-processing unit 207 subjects the image data of the pictures to interpolation or sub sampling to match the frame rate with the display capability. The image data of the pictures processed by the post-processing unit 207 is supplied to the display unit 208 for display of moving images.

As described above, in the transmission/reception system 10 illustrated in FIG. 1, the transmission device 100 equalizes the hierarchical composition between the low-level side and the high-level side, and combines corresponding pictures on the low-level side and the high-level side into one set and encodes the same sequentially. Accordingly, the reception device 200 can decode the encoded image data of the pictures on the low-level side and the high-level side at one collective timing, thereby reducing the buffer size and decreasing decode delay.

In addition, in the transmission/reception system 10 illustrated in FIG. 1, the transmission device 100 inserts the hierarchical information into the layer of the container to generate a transport stream containing a video stream having the image data of the encoded pictures at the respective levels. Accordingly, the reception device 200 can refer to the hierarchical information to retrieve selectively from the video stream the encoded image data of the pictures up to the level commensurate with the capability of the decoder in an easy manner, for example.

In the transmission/reception system 10 illustrated in FIG. 1, the transmission device 100 inserts the hierarchical information into the PES extension field of the header of the PES packet in the position synchronized with the encoded image data of the pictures of the video stream at least for each coded video sequence (CVS). This allows the reception side to, even with changes in the hierarchical composition, retrieve selectively from the video stream the encoded image data of the pictures up to the level commensurate with the capability of the decoder.

FIG. 18 illustrates an example of correspondence between signaling of “level_idc” and hierarchical information of encoded image data with changes in hierarchical composition. In this example, the hierarchical composition changes from a first 50P CVS system in which encoding is performed at three levels of 0 to 2 to a second 50P CVS system in which encoding is performed at four levels of 0 to 3, and further changes to a 100P CVS system in which encoding is performed at six levels of 0 to 5. In the illustrated example, the hierarchical information is inserted under the PMT. However, the foregoing matter also applies to the case where the hierarchical information is inserted under the EIT or into the PES extension field as described above.

In the period of the first 50P CVS system, data is distributed in a single video stream. The value of “general_level_idc” inserted into the SPS of the encoded image data is set to “Level 5.1” as a level value containing all the pictures at the levels of 0 to 2. The value of “sublayer_level_idc[1]” as the level specified value of bit rate at the level of 1 is set to “Level 5.” In this case, the hierarchical information is described as “layer_level_idc[0]”=Level 4.1, “layer_level_idc[1]”=Level 5, and “layer_level_idc[2]”=Level 5.1.”

In the period of the second 50P CVS system, data is distributed in a single video stream. The value of “general_level_idc” inserted into the SPS of the encoded image data is set to “Level 5.1” as a level value containing all the pictures at the levels of 0 to 3. The value of “sublayer_level_idc[2]” as the level specified value of bit rate at the level of 2 is set to “Level 5.” In this case, the hierarchical information is described as “layer_level_idc[0]”=Level 4, “layer_level_idc[1]”=Level 4.1, “layer_level_idc[2]”=Level 5″, and “layer_level_idc[3]”=Level 5.1.”

In the period of the 100P CVS system, data is distributed in two video streams. The value of “general_level_idc” inserted into the SPS of the encoded image data is set to “Level 5.2” as a level value containing all the pictures at the levels of 0 to 5. The value of “sublayer_level_idc[2]” as the level specified value of bit rate at the level of 2 is set to “Level 5.1.” In this case, the hierarchical information is described as “layer_level_idc[0]”=Level 4.1, “layer_level_idc[1]”=Level 5, “layer_level_idc[2]”=Level 5.1, “layer_level_idc[3]”=Level 5.2, “layer_level_idc[4]”=Level 5.2, and “layer_level_idc[5]”=Level 5.2.”

While the hierarchical composition changes as illustrated in the drawing, if the decoder 205 of the reception device 200 corresponds to 50P, for example, the demultiplexer 203 retrieves the levels of 0 to 2 in the period of the first 50P CVS system, retrieves the levels of 0 to 3 in the second 50P CVS system, and retrieves the levels of 0 to 2 in the period of the 100P CVS system, based on the hierarchical information, and sends the same to the compressed data buffer 204. The decoder 205 decodes the encoded image data of the pictures at their respective decode timings to obtain 50P image data.

<2. Modification Example>

In the foregoing embodiment, the transmission/reception system 10 is composed of the transmission device 100 and the reception device 200. However, the configuration of the transmission/reception system to which the subject technique is applicable is not limited to this. For example, part of the reception device 200 may be formed as a set-top box and a monitor connected via a digital interface such as a high-definition multimedia interface (HDMI). The “HDMI” is a registered trademark.

In the foregoing embodiment, the container is a transport stream (MPEG-2 TS). However, the subject technique is also applicable to other systems in which data is distributed to reception terminals via a network such as the Internet. In the Internet delivery, data is frequently distributed by a container in MP4 or other formats. That is, the container may be a transport stream (MPEG-2 TS) employed under digital broadcasting standards, or any other container in various formats such as MP4 used in the Internet delivery.

The subject technique may be configured as described below.

-   (1) A transmission device including:

an image encoding unit that classifies image data of pictures constituting moving image data into a plurality of levels and encodes the classified image data of the pictures at the respective levels to generate a video stream having the encoded image data of the pictures at the respective levels; and

a transmission unit that transmits a container in a predetermined format containing the generated video stream, wherein

the image encoding unit equalizes hierarchical composition between a low-level side and a high-level side, and combines corresponding pictures on the low-level side and the high-level side into one set and encodes the same sequentially.

-   (2) The transmission device according to (1), further including

a hierarchical information insertion unit that inserts hierarchical information into a layer of the container.

-   (3) The transmission device according to (2), wherein

the hierarchical information has information on level specified values for the respective levels.

-   (4) The transmission device according to (2) or (3), wherein

the hierarchical information insertion unit inserts the hierarchical information into the layer of the container at positions in synchronization with the encoded image data of the pictures in the video stream.

-   (5) The transmission device according to (4), wherein

the hierarchical information insertion unit inserts the hierarchical information into an extension field of a PES packet.

-   (6) The transmission device according to (5), wherein

the hierarchical information insertion unit inserts the hierarchical information into the extension field of the PES packet at least for each coded video sequence.

-   (7) The transmission device according to (5) or (6), further     including

an information insertion unit that inserts information for describing explicitly whether the hierarchical information is inserted into the extension field of the PES packet under a program map table.

-   (8) The transmission device according to (2) or (3), wherein

the hierarchical information insertion unit inserts the hierarchical information under a program map table.

-   (9) The transmission device according to (2) or (3), wherein

the hierarchical information insertion unit inserts the hierarchical information under an event information table.

-   (10) The transmission device according to any of (1) to (9), wherein

the image encoding unit generates a single video stream having the encoded image data of the pictures at the respective levels or divides the plurality of levels into two sets of the upper-level side and the lower-level side and generates two video streams having the encoded image data of the pictures in the respective level sets.

-   (11) A transmission method including:

an image encoding step of classifying image data of pictures constituting moving image data into a plurality of levels and encoding the classified image data of the pictures at the respective levels to generate a video stream having the encoded image data of the pictures at the respective levels; and

a transmission step by a transmission unit of transmitting a container in a predetermined format containing the generated video stream, wherein

at the image encoding step, hierarchical composition is equalized between a low-level side and a high-level side, and corresponding pictures on the low-level side and the high-level side are combined into one set and are sequentially encoded.

-   (12) A reception device including a reception unit that receives a     container in a predetermined format that contains a video stream     having encoded image data of pictures obtained by classifying image     data of the pictures constituting moving image data into a plurality     of levels and encoding the same, wherein

in the encoding, hierarchical composition is equalized between a low-level side and a high-level side, and corresponding pictures on the low-level side and the high-level side are combined into one set and are sequentially encoded, and

the reception device further includes a processing unit that processes the received container.

-   (13) The reception device according to (12), wherein

hierarchical information is inserted into a layer of the container, and

the processing unit retrieves selectively from the video stream the encoded image data of the pictures at a predetermined level and lower ones and decodes the same, based on the hierarchical information, to obtain the image data of the pictures at the predetermined level and lower ones.

-   (14) A reception method including a reception step by a reception     unit of receiving a container in a predetermined format containing a     video stream that has encoded image data of pictures at a plurality     of levels obtained by classifying image data of the pictures     constituting moving image data into the respective levels and     encoding the same,

in the encoding, hierarchical composition is equalized between a low-level side and a high-level side, and corresponding pictures on the low-level side and the high-level side are combined into one set and are sequentially encoded, and

the reception method further includes a processing step of processing the received container.

INDUSTRIAL APPLICABILITY

A main feature of the subject technique is in that the hierarchical composition is equalized between the low-level side and the high-level side, and corresponding pictures on the low-level side and the high-level side are combined into one set and are sequentially encoded, thereby allowing the reception side to decode the encoded image data of the pictures on the low-level side and the high-level side with a smaller buffer size and a reduced decoding delay (see FIGS. 3 and 5). Another main feature of the subject technique is in that the hierarchical information is inserted into the layer of the container to allow the reception side to retrieve selectively from the video stream the encoded image data of the pictures up to the level commensurate with the capability of the decoder in an easy manner (see FIGS. 7(a) and 7(b), and FIGS. 11 to 16).

REFERENCE SIGNS LIST

-   10 Transmission/reception system -   100 Transmission device -   101 CPU -   102 Encoder -   103 Compressed data buffer (cpb) -   104 Multiplexer -   105 Transmission unit -   200 Reception device -   201 CPU -   202 Reception unit -   204 Compressed data buffer (cpb) -   205 Decoder -   206 Decompressed data buffer (dpb) -   207 Post-processing unit -   208 Display unit 

The invention claimed is:
 1. A transmission device comprising: an encoder configured to: perform hierarchical encoding on image data of pictures constituting moving image data to generate a first stream having encoded image data of pictures on a low-level side and a second stream having encoded image data of pictures on a high-level side, the encoded image data having a network abstraction layer (NAL) unit structure, and insert a level specified value of the first stream together with a level specified value of a bit stream formed from a combination of the first stream and the second stream into a sequence parameter set (SPS) NAL unit of the first stream, the level specified value of the first stream being discrete from the level specified value of the bit stream formed from the combination of the first stream and the second stream; a multiplexer configured to: multiplex the first stream and the second stream generated by the image encoding unit to obtain a container in a predetermined format, insert a first descriptor describing the level specified value of the first stream into the container at a first position other than in the SPS NAL unit and in correspondence with the first stream, and insert a second descriptor describing the level specified value of the bit stream formed from the combination of the first stream and the second stream into the container at a second position other than in the SPS NAL unit and in correspondence with the second stream; and a transmitter configured to transmit the container in the predetermined format obtained by the multiplexer.
 2. The transmission device according to claim 1, wherein the first descriptor further describes maximum and minimum information on the levels of the pictures contained in the first stream, and the second descriptor further describes maximum and minimum information on the levels of the pictures contained in the second stream.
 3. The transmission device according to claim 1, wherein the container is a transport stream, and the first descriptor and the second descriptor are inserted under a program map table.
 4. The transmission device according to claim 1, wherein flag information indicative of insertion of the level specified value of the first stream is further inserted into the SPS.
 5. A transmission method comprising: performing hierarchical encoding on image data of pictures constituting moving image data to generate a first stream having encoded image data of pictures on a low-level side and a second stream having encoded image data of pictures on a high-level side, the encoded image data having a network abstraction layer (NAL) unit structure; inserting a level specified value of the first stream together with a level specified value of a bit stream formed from a combination of the first stream and the second stream into a sequence parameter set (SPS) NAL unit of the first stream, the level specified value of the first stream being discrete from the level specified value of the bit stream formed from the combination of the first stream and the second stream; and multiplexing the first stream and the second stream generated at the image encoding to obtain a container in a predetermined format; inserting a first descriptor describing the level specified value of the first stream into the container at a first position other than in the SPS NAL unit and in correspondence with the first stream; inserting a second descriptor describing the level specified value of the bit stream formed from the combination of the first stream and the second stream into the container at a second position other than in the SPS NAL unit and in correspondence with the second stream; and transmitting the container in the predetermined format obtained at the multiplexing.
 6. A reception device comprising: a receiver configured to receive a container in a predetermined format containing: a first stream having encoded image data of pictures on a low-level side and a second stream having encoded image data of pictures on a high-level side generated by performing hierarchical encoding on image data of pictures constituting moving image data, and a first descriptor describing a level specified value of the first stream positioned at a first position other than in a sequence parameter set (SPS) network abstraction layer (NAL) unit of the first stream and in correspondence with the first stream and a second descriptor describing a level specified value of a bit stream formed from a combination of the first stream and the second stream positioned at a second position other than in the SPS NAL unit and in correspondence with the second stream, wherein the encoded image data has a NAL unit structure, and the level specified value of the first stream is inserted together with the level specified value of the bit stream formed from the combination of the first stream and the second stream into the SPS NAL unit of the first stream, the level specified value of the first stream being discrete from the level specified value of the bit stream formed from the combination of the first stream and the second stream; and a processor configured to decode the first stream or both the first stream and the second stream contained in the received container depending on a decoding capability to obtain the image data of the pictures constituting moving image data.
 7. A reception method comprising: receiving a container in a predetermined format containing a first stream having encoded image data of pictures on a low-level side and a second stream having encoded image data of pictures on a high-level side generated by performing hierarchical encoding on image data of pictures constituting moving image data, and a first descriptor describing a level specified value of the first stream positioned at a first position other than in a sequence parameter set (SPS) network abstraction layer (NAL) unit of the first stream and in correspondence with the first stream and a second descriptor describing a level specified value of a bit stream formed from a combination of the first stream and the second stream positioned at a second position other than in the SPS NAL unit and in correspondence with the second stream, wherein the encoded image data has a NAL unit structure, and the level specified value of the first stream is inserted together with the level specified value of the bit stream formed from the combination of the first stream and the second stream into the SPS NAL unit of the first stream, the level specified value of the first stream being discrete from the level specified value of the bit stream formed from the combination of the first stream and the second stream; and decoding the first stream or both the first stream and the second stream contained in the received container depending on a decoding capability to obtain the image data of the pictures constituting moving image data. 